Electrically heated soldering apparatus



Dec. 14, 1943. G. L. WARD 2,336,904

ELECTRICALLY HEATED SOLDERING APPARATUS Filed July 17, 1942 PatentedDec. 14, 1943 ELECTRICALLY HEATED SOLDERING APPARATUS George Louie Ward,Northwood, England, assignor to International Standard ElectricCorporation, New York, N. Y.

Application July 17, 1942, Serial No. 451,295 In Great Britain July 18,1941 4 Claims.

This invention relates to tools for electric soldering.

A description will now be given of the accompanying drawing, in which,

Fig. 1 is a side view of an electric soldering tool made in accordancewith the invention;

Fig. 2 is a front view thereof, and

Fig. 3 is an end View of a part, namely the bithlder.

Referring to the drawing, two conducting arms II and I2 extend forwardlyin parallel one above the other from a clamp I3 at their rear end. Theupper arm II enters at its extremity into a tool-bit holder I4 made ofsteel, being riveted and brazed thereto to ensure a good mechanical andelectrical connection. The bit holder I4 is in the shape substantiallyof a rectangular block lying in the plane of the ends of the arms andhence normal to the arms themselves, a lug I5 being provided at themiddle of its top edge to receive the upper conducting arm. The bottomedge has a slot I6 formed therein, extending from one end nearly but notquite to the other. This slot is of key-hole shape when viewed from theend, that is to say it has a lower portion with straight sides runningright to the bottom edge, and an upper portion which has the shape insection of a circle lying wholly within the body of the metal.

The soldering bit I"! is of copper, and is combshaped, the back of thecomb being located Within the lower straight-sided portion of thekeyhole slot I6 and the teeth extended downwardly from the bottom edgeof the bit holder. Grub screws I8 pass through the front of the bitholder near its bottom edge to fix the comb in place.

Within the upper circular-sectioned portion of the slot I6 is located acarbon rod which is of high-resistance carbon and which constitutes theheating element. At the innermost end the slot I6 is conical, coming toa point at about an angle of 60, and into this cone fits the similarlypointed end of the carbon rod which is thus, at that end, accuratelycentered. Near the outer end the circular portion of the slot isenlarged a little at I9, and into the enlarged portion is fitted a shortsleeve of heat and electrical insulating material such as Vitroesilhaving a bore smaller than the slot in which the carbon rod is a closelit 50 that its outer end also is accurately centered. Behind the carbonrod is a conducting plug 2!), preferably of silver steel, which fitscomfortably in the slot and which is tapered at its inner end where itengages the carbon.

The second of the two conducting arms, the

lower one I2, is bent so that its forward extremity overlies the mouthof the circular-sectioned slot in the end of the bit-holder l4, and isprovided with a diametrical hole which is coaxial with the slot. Throughthis hole passes the conducting plug 20, being fixed by a screw 2|passing into the end of the arm.

The rear ends of the two conducting arms II and I2 are connected tocurrent supply leads 22 and 23, the supply being preferably of lowvoltage and large current value, as would be obtainable from a step-downtransformer fed from commercial mains. When the supply is switched on,the current will flow in a circuit consisting of the upper arm I I, thebit holder I4, the conical point on the inner end of the carbon rod, thelength of the carbon rod itself, the plug 20, and the lower arm I2. Thecarbon, being of high resistance, will heat up, and the heat will beconducted to the teeth of the comb I'I. Except at its ends, the carbonrod is out of contact with either the bit-holder or the bit, otherwise ashort-circuit of the current would occur.

The comb soldering bit can be made to suit any multi solderingoperation, and in any shape, to suit the parts to be soldered. Again,the soldering head can also be made with two or more sets of combseachsoldering comb heated by a separate carbon electrode.

With this method of soldering, the soldering medium, such as flux andsolder foil can be placed on the part to be soldered, and the solderingcomb used solely for the purpose of applying the necessary heat to carryout the soldering operation. This would also apply to the application ofsolder paste. This process is possible because, with the comb type ofsoldering bit heated by a carbon electrode, soldering temperature isquickly attained, and a uniform heat is distributed over the entirelength of the comb and maintained during the operation.

The tool head can be used, or adapted for use, with either ahand-operated or foot-operated machine.

What is claimed is:

1. An electric soldering tool comprising, a substantially-rectangularbit-holder of steel, an electrical connection from one current lead tosaid bit holder, a bit of copper with its rear portion located in thestraight-sided portion of a keyhole slot in the bit-holder, acircular-section rod of carbon located in the circular-section portionof said key-hole slot and engaging the bit-holder only at the inner endwhere a point on the rod fits into a conical recess in the slotend-wall, a

tending forwardly in parallel from a clamp at their rear end.

3. An electrical soldering tool as claimed in claim 1, in which the bitis comb-shaped.

4. An electrical soldering tool as claimed in claim 1, in which the plugis of silver steel.

GEORGE LOUIE WARD.

